The English domestic cricket season could be radically restructured to feature a three-conference county championship, a 21-team Twenty20 league and a revamped Pro 40 competition of two 20-over innings per side under proposals to be considered by the ECB board this week.

The board is due to meet on Thursday to discuss changes to the domestic structure from 2010, and the revolutionary proposals are among a number of options that will be considered. Also on the table will be Jack Simmons' suggestion of a return to three-day championship games, a return to a single division with all teams playing each other once and maintaining the two- division status quo.

The ECB has drawn up the plans in response to the Twenty20 phenomenon and the rise of the Indian Premier League, which has transformed the commercial expectations of players and county chairmen. While the county championship is of little commercial value, reform is crucial to free up time in the calendar for an extended mid-summer English Premier League.

Broadcasters, sponsors and other commercial partners will be consulted about the possible changes to the current structure as the ECB prepares to issue a revised tender document for broadcast rights.

As well as the revamped domestic competitions the ECB is also committed to accommodating a four-nation quadrangular T20 tournament bankrolled by the Texan billionaire Sir Allen Stanford. The future of the only 50-over one-day tournament, the Friends Provident Trophy, will also have to be considered.

Broadcast revenue will be the key to establishing a viable English premier league and the ECB has been forced to reconsider its original broadcast tender, issued before the IPL revealed the commercial potential of Twenty20. The priority is to develop a structure that allows the leading players to take part in the EPL without affecting their international commitments.

The ECB's current £220m deal with Sky, Five and the BBC runs out at the end of next season. With the Ashes and the ICC World Twenty20 due to be played in England next summer the changes will not be introduced until the following year but the ECB is under pressure to flesh out its plans.

At the heart of discussions has been how to accommodate a viable EPL that will enable the ECB to compete with the revenues being generated in India.

The radical three-conference proposal has been drawn up as an illustration of how a revised season might look and there has been considerable interest from broadcasters.

Though the board will discuss the changes this week, no decision will be taken on the EPL and the Pro40 competition until it has seen the results of market research that will be carried out during the coming T20 competition.

There is consensus emerging around the options for an English Premier League, however. The ECB chairman, Giles Clarke, is adamant that regional or city-based franchises are not appropriate for the English game, not least because the ECB has a constitutional requirement to serve all 18 first-class counties.

There is enthusiasm for adding three overseas teams to the EPL, including the IPL champions, to boost interest from overseas broadcast markets, which would take the total number of teams to 21. It is thought that a league system would be used initially with a knockout phase deciding the champions.

The proposal to revamp the Pro40 reflects the fact that, while the format is incongruous - no international cricket is played over that distance - it is popular with supporters and relatively lucrative for counties.

Restructuring the first-class championship into three conferences could be arranged with three six-team southern, midland and northern divisions or selected on the basis of performances in previous seasons.